Personalized markup for protecting numerical audiovisual streams

ABSTRACT

A process for distributing a video stream to a multitude of destinations including marking by adding to the video stream at least a visual element such that the marking is applied to an original video stream common to selected recipients, and personalized for a least portion of the recipients by addition of a visual element specific to destination equipment.

RELATED APPLICATION

This is a continuation of International Application No.PCT/FR2003/050193, with an international filing date of Dec. 19, 2003(WO 2004/062281, published Jul. 22, 2004), which is based on FrenchPatent Application No. 02/16918, filed Dec. 31, 2002.

FIELD OF THE INVENTION

This invention relates to a device capable of transmitting in a securedmanner a collection of numerical images of high visual quality to adisplay and/or for storing in the memory of a back-up device thatconnects a transmission network to the display while preserving thevisual quality, but avoiding fraudulent use such as the possibility ofmaking unauthorized copies of the films or audiovisual programs.

BACKGROUND

A general problem in the art is to provide a procedure capable oftransmitting in a secured manner audiovisual and multimedia data of highvisual quality and in whatever numerical format, live or prerecorded, toa television screen, video projector or for being recorded on a harddisk or a completely different back-up device belonging to a box thatconnects the remote transmission network to a display of a type ofmonitor, television screen, video projector, or projection screen, allwhile preserving the audiovisual quality, but avoiding fraudulentutilization such as the possibility of making pirated copies, analog ornumerical, of the films or audiovisual programs visualized via theaforementioned decoder box.

The demand for interactive multimedia services is more and moreimportant. The distribution systems of multimedia information on DVDs oron the telecommunication network, for example, video on demand systemsare in full expansion and characterized by their complexity and theirinsecurity with respect to pirating in spite of numerous existingprocedures and systems. These distribution systems are often veryexpensive to implement by the user, lack security, flexible usage, andthe adaptability to different clients and their needs. Moreover, theyare often pirated by mal-intentioned persons in spite of the variousprotection or traceability procedures, such as “watermarking.”“Watermarking,” also called digital watermarking, is a technique thatjoins the visual or audio content, the digital content such as images,the video or audio streams. The technique consists of processing thecontents to insert information in the contents. In general, the insertedinformation is invisible at the time of seeing the content, but can beretrieved by applying the processing of the aforementioned content. Twotypes of watermarks exist:

the fragile watermark: The inserted information is affected by amodification of the content; this type of watermark is used to detect ifthe contents have been modified;

the robust watermark: The inserted information is itself conserved evenif the content is modified; this type of watermark is, for example, usedto associate the royalties of an author with a work.

Certain holders of films or audiovisual programs make fraudulent copieswhich they then distribute via various supports (Internet, DVDspirates). Indeed, the majority of current protection systems rely solelyon protection through encrypting a digital stream. However, once decodedon the client station, the film is no longer protected and can be copiedon other supports such as a simple VHS cassette, for example, with avideo tape recorder connected between the video output of the decoderand the television set.

Different watermarking solutions exist that withstand the variousmanipulations that the aforementioned fraudulent copy can undergo tocorrect this problem. However, it does not permit the immediateidentification of the person at the origin of the copy and, thus, thefraudulent broadcast. Copying and distribution of the piratedaudiovisual programs continues without an immediate and simple visualidentification of the coordinates of the persons at the origin of thefraud.

With existing solutions, it is possible to transmit films andaudiovisual programs in digital form via broadcasting networks of typewireless, cable, satellite, etc., or via the telecommunication networksof type DSL or (Digital Subscriber Line) or LLR. (Local Loop Radio) orvia DAB (Digital Audio Broadcasting), etc., networks. In addition, toavoid the pirating of works broadcasted in this way, the latter areoften encrypted or scrambled through various well known means.

However, a main inconvenience of current solutions is that in the caseof pirating of the protection system, particularly by systems offalsified chip cards or by the simulation of the encryption keys, theaudiovisual works are susceptible to being broadcasted in anuncontrolled way in a perfect digital form, that is, in every respect inconformity with the original. Moreover, a single pirated copy of such anaudiovisual program can enable the pirate, who is at the origin, tocommercialize on a large scale the pirated work because it is perfect.

One solution consists of digitally marking the distributed digitalcopies. For example, US 2002/129253 discloses a procedure for processinga compressed MPEG stream that consists of directly marking thecompressed MPEG signal by the modification of the values present in thestream according to a watermarking motif. However, that type ofprocedure does not guarantee that the mal-intentioned user could notcreate a copy of the protected film in another form that is differentfrom the form in which it was supplied. In particular, those proceduresdo not guarantee the impossibility of producing copies of the films inthe form of VHS cassettes that allow commercialization of the illicitcopies. In the same way, they do not prevent production of copies offilm in compressed numerical forms of the DivX or VCD type, which areone of the principal supports of pirated films available on theInternet.

WO 97/46012 discloses marking audiovisual streams based on small spatialdistortions of the pixels of the video images according to selecteddeformation motifs. That type of marking is invisible to the eye andpermits the transmission of information in the video stream without theknowledge of the person that uses it. The information permitsidentification of the source and date of an unauthorized copy of thevideo image. That type of modification is also envisaged to resist achange of support of the video, in particular, with a support on a VHScassette, or change of format in DivX or VCD.

U.S. Pat. No. 4,528,588 discloses transmission of an encoded audiovisualsignal, for example, by systems of known keys, wherein theaforementioned signal is decoded on the destination equipment and at thesame time marked by identification information specific to the clientequipment or its possessor. The aforementioned information is beingintroduced in such a way, spatially and frequentially, that itsextraction is made difficult. The aforementioned information moreoverbeing more obligatorily inserted in the stream thanks to a systemimplying a magnetic or chip card which contains at the same time thenumerical keys necessary to decoding of the aforementioned signal andinformation of identification to be inserted.

The call for the decoding keys cannot be done without usingidentification information. The mark inserted in the stream is a binaryword inserted with a system of modifications of the levels of the videosignal at certain quite precise places, known to a specific device thatis in charge of locating the aforementioned mark in a video stream. Themark is more invisible to complicate the task of a mal-intentionedindividual who wishes to extract it. Any copy of a film thus protected,in whatever form it may be, contains the same mark as the copy of thesignal from which it resulted. Thus, if a copy of a signal is identifiedas pirated, one can identify the person and the equipment at the originof the fraudulent copy and, thus, condemn it. The correspondence betweena mark and the individual holder of the copy is realized thanks to adata base, contained on a server contacted at the time of the renting ofthe video.

However, these solutions all have in common that they require thecomparison between the copy of origin of a film and the copy pirated tobe able to identify the mark inserted in the signal. This implies acentralization of the tests of identification in a place where theoriginal, or the distribution of a great number of copies of theoriginal, would be stored. In those cases, that poses practical problemsand the identification of the source of a copy can, thus, becomelaborious.

Moreover, those solutions necessitate specific hardware and, as aconsequence, specialists to carry out the identification. Indeed, manyefforts are made to make the inserted mark as discrete as possible toprevent pirates from locating it and, thus, extracting it. However, themore difficult it is for a pirate to locate the mark, the more itrequires complex hardware on the verification side. This is because thepirate would otherwise be able to constitute his own apparatus and thuscounter the protection system. In such cases, this poses practicalproblems and makes identification of the source of a pirated copylaborious to obtain.

Lastly, those solutions hardly dissuade pirates from proceeding to makecopies. Indeed, the inserted marks being invisible, pirates believe thatthey can succeed by handling the original video via changes in supportsor operations. The pirate is all the more inclined to do it because thepirate knows that very few pirated copies will be tested and identifiedbecause the associated methods of identification are very difficult.Thus, even if the mark resists such manipulation, the pirate risksalmost nothing in any case. With the current limitations of the currentsystems, many individuals do not hesitate to pirate and distributefraudulent film copies.

It would therefore be advantageous to provide a protected system todissuade pirates from making fraudulent copies and especially dissuadepirates from dispersing pirated works to other people.

SUMMARY OF THE INVENTION

This invention relates to a process for distributing a video stream to amultitude of destinations including marking by adding to the videostream at least a visual element such that the marking is applied to anoriginal video stream common to selected recipients, and personalizedfor a least portion of the recipients by addition of a visual elementspecific to destination equipment.

This invention also relates to an apparatus for distributing a videostream marked according to the process for distributing a video streamto a multitude of destinations, including a standard decoding module ofa format of the video stream, and a composition module that interpretsthe markup data and includes the visual element in the video stream.

This invention further relates to a system for fabricating a markedstream according to the process for distributing a video stream to amultitude of destinations, including equipment for distributing a videostream including a standard decoding module of a format of the videostream, and a composition module that interprets the markup data andincludes the visual element in the video stream, a storage device, amarkup data storage device, a display device of the video stream and astorage device of the modified video stream.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood upon reading thedescription of the, not limiting, realization examples that follow,while referring to the attached drawings where:

FIG. 1 schematically shows the architecture of a unit of a system forimplementing a procedure according to aspects of the invention;

FIG. 2 schematically shows the architecture of a sub unit of a systemfor setting in motion a procedure according to aspects of the invention;and

FIG. 3 represents a particular mode of realization of a flux synthesissystem conforming to aspects of the invention.

DETAILED DESCRIPTION

This invention concerns a process of distributing video streams to aplurality of recipients, comprising a stage of marking comprising addingto the aforementioned video stream at least a visual elementcharacterized in that the aforementioned stage of marking is applied toan original video stream common to all recipients, and is personalizedfor at least a part of the recipients by adding a visual elementspecific to the destination client equipment.

According to one mode of realization, the aforementioned visual elementis generated in two stages, a first stage comprising processing themarking data in whatever format to generate marking objects describingthe visual element to display, and a second stage comprising adding theaforementioned visual element to the aforementioned video stream.

Moreover, the stage of addition of the aforementioned visual element isaccompanied by a stage of invisible modifications.

In another aspect, at least one of the aforementioned stages of additionis carried out before the decoding of video stream in the destinationequipment. In another aspect, at least one of the aforementioned stagesof addition is carried out after decoding the video stream in thedestination equipment.

Advantageously, the aforementioned invisible modifications arecharacteristic of a digital signature, the aforementioned digitalsignature being detectable by an algorithm appropriate to detectionapplied to the stream containing the aforementioned invisiblemodifications. Preferably, the aforementioned digital signature isobtained from the markup data.

Advantageously, the markup data are different and personalized for everyclient. In the same way, the aforementioned visual element introduced inthe aforementioned video stream may be different and personalized forevery client.

The aforementioned visual element may also be an identifier of theclient that is visible at the time of the display of the marked videostream. Alternatively, the visual element includes a message destinedfor the client.

Advantageously, the stage of generation of the markup objects the markupdata makes it possible to vary the position on the screen, the color,spacing, the geometry, and the presence of the aforementioned visualelement, during the display of all or part of the aforementioned videostream.

The stage of adding the aforementioned visual element to theaforementioned video stream may be carried out on the multi-media serverequipment from which the aforementioned video stream is dispatched tothe client in a later phase. The stage of adding the aforementionedvisual element to the aforementioned video stream may also be carriedout on the client equipment.

The markup data may come from a server that protects the audiovisualrights at the time of visualization of the aforementioned video stream.Also, the markup data may come from a module present on the clientequipment.

Advantageously, visualization of the aforementioned video stream isconditioned by connecting to the aforementioned server that protects theaudiovisual rights and a server is connected to a data base of clientprofiles including the markup data associated with each client.

The invention also concerns equipment for distributing a marked videostream comprising a module of standard decoding of the format of theaforementioned video stream and a module of composition in charge ofinterpreting the markup data and including the aforementioned visualelement in the aforementioned video stream.

Advantageously, the aforementioned equipment comprises a chip cardreader connected to a chip card that contains the aforementioned markupdata.

This invention further concerns a system for fabricating a marked streamcomprising equipment for distributing a video stream, a means, linked tothe aforementioned equipment, to store the aforementioned video stream,a means, linked to the aforementioned equipment, to store theaforementioned markup data, a display device of the aforementioned videostream and a device to store the modified video stream.

One general principle of a process to secure a video stream is presentedhereafter.

The general idea is to introduce a visual marking in the video streamwith the aid of new data called “markup data,” information or messages,personalized and targeted as a function of every user, the user'srights, the application and the use that made of the audiovisual flux.

With prior solutions, it is possible to transmit films and audiovisualprograms in digital form via broadcasting networks of type wireless,cable, satellite or the like or via telecommunication networks of theDSL (Digital Subscriber Line) or LLR (Local Loop Radio) type, via DABnetworks (Digital Audio Broadcasting) or via digital communicationnetworks (GSM, GPRS, UMTS) or the like. In addition, to avoid piratingof works broadcast, these last are often encrypted by various well-knownmeans. In a general sense, the systems offering the audiovisual servicesare based on the principle of a client-server system, whose nodes areconnected by a telecommunications network. The client addresses theserver through a user interface to request audiovisual content, oraudiovisual content that is already at the user. The server, as afunction of the rights of the user, sends the audiovisual content and/orthe decoding key(s) to the client. Once the film is decoded at theclient, it is visualized and can be easily copied and sent to otherusers, without the possibility of control, follow-up, traceability orverification.

The aforementioned “watermarking” depends advantageously on theterminals on which the video program is played or streamed. Thedisadvantage of those solutions is that one cannot surprise the peoplewho look at a pirated film without having to apply a suitable tool fordetecting watermarking. This has as the consequence that only a team ofspecialists, equipped with adapted tools, is able to prove theculpability of a pirate by showing that the pirate had a private copy ofa video program which the pirate duplicated and distributed.

This invention introduces into the video stream a visible element, whichis hereinafter referred to as a “visual element” and is directlycomprehensible to any human being, of the type text, image, or videoobject, in a personalized way, for each user, each terminal and eachviewing session, to be able to determine immediately if the user hasrights to the films viewed by a simple identity check, and to alsoprevent the user from distributing the film without authorization toother people.

Several alternatives of this process of insertion of visual andpersonalized elements in a digital video stream may be employed in thisinvention.

A first alternative is the insertion of a visual element during thereading and display of a digital film which is or is not encrypted. Thecomposition module, in charge of the insertion of the visual element,integrated in the digital video decoder, on the request for reading anddisplay on behalf of the client, automatically introduces a visualelement into the digital stream. This visual element can be of varioustypes: an image, a logo, a text, a video or the like. The visual elementis either fixed on a given location of the screen, or moving on thescreen during the film. Advantageously, its form, its type, and itsappearance change. Its presence on the screen is either permanent orepisodic. Advantageously, the visual element creates a direct link withthe user, by displaying for example name, telephone number or address.The aforementioned element, in this case being generated thanks to theprocessing of markup data from the hard disk or the memory dedicated tothe software for the display of the stream and/or a chip card insertedin the client equipment. The markup data are binary data describing thecontent of the element to be displayed such as, for example, the name ofthe client, address or telephone number, or even an image or a videocontaining the same information cited previously. These markup data areadvantageously encrypted.

Another variation is where the aforementioned markup data are obtainedby the client equipment from a server that protects audiovisual rights.Therefore, when the client connects to the server that protects theaudiovisual rights at the desired moment to watch the video programwhich is in the client's possession, the aforementioned server sendsmarkup data to the client which will be treated and interpreted by thecomposition module of the client equipment, which will result in thedisplay of a visual element, specific to the client, on a displayscreen.

In another aspect, the box “Set-Top-Box” (STB), serving as an interfacedevice between the display device of the client and the multi-mediaserver, which contains the video program that the aforementioned clientwishes to watch, contains a composition module. After the command andthe downloading of video film from the multi-media server, the STBcontaining the profile of the client (identity, rights, practices)inserts a visual element during reading and display of the film. In thecase that the STB does not have the profile of the client, it will seekthe markup data in a data base of the server concerning the downloadedfilm and the profile of the client, and decides to engrave the visualelement.

Another aspect is the integration of the composition module in themulti-media server. The client connects to a multi-media server andorders a film, the server sends an encrypted film in a personalized waythat contains a specific personalized visual element and asks theclient, for example, to pay for the rights to view the film. When theclient rights are in order, the watched film contains a visual andpersonalized element that is specific to the client and identifies theclient.

Another aspect is where the client equipment connects to a server thatprotects the audiovisual rights containing information necessary forviewing the film such as, for example, the keys necessary for itsdecoding. The aforementioned server sends personalized numericalinformation containing the key necessary for decoding and the markupdata relating to the client, which allows the reconstruction of the filmon which a visual element of identification, specific to the client, isaffixed.

Yet another aspect concerns a process for distributing digital videosequences according to a nominal stream format consisting of asuccession of frames, each including at least one numerical blockgathering a certain number of coefficients corresponding to simple videoelements encoded numerically according to a mode specified inside theconcerned stream and used by all the video decoders that are able todecode it to be able to display it correctly. This procedure includes:

a preparatory stage comprising modifying, at least, one of theaforementioned elements (for example the coefficients); and

a transmission stage:

-   -   of a principal stream conforming to a nominal format, including        the plans containing the blocks that are modified during the        preparatory stage and    -   through a channel separate from that of the aforementioned        complementary numerical information that allows reconstruction        of the original stream through a calculation on the destination        equipment, as a function of the aforementioned principal stream        and the aforementioned complementary information. The        aforementioned “complementary information” is defined as a        collection comprising data (for example, the coefficients        describing the original numerical stream or extracts of the        original stream) and functions (for example, the substitution or        permutation function). One function is defined to contain at        least one instruction that matches up the data and the        operators. The aforementioned complementary information        describes operations that must be executed to recover the        original stream from the aforementioned modified stream.

Reconstruction of the original stream takes place on the destinationequipment (the STB) from the modified principal stream that is alreadypresent on the destination equipment and from the, in real timedispatched, complementary information that comprises data and functionsexecuted with the aid of numerical routines (collections ofinstructions). The complementary information contains, moreover, themarkup data and numerical routines relating to the visual elements thathave to be inserted in the film. The insertion of visual elements takesplace in real time during descrambling of the film in the STB and duringits display on the screen.

In another aspect, the complementary information that is sent to thedestination equipment by the server does not contain the data andfunctions that allow display of the original stream at places andmoments corresponding to the display of a visual element. For example,if a visual element is displayed in the central part of the image, thecomplementary information that is sent to the destination equipment willnot contain the data and functions which would have allowed a displayidentical to that of the original stream for the aforementioned party.In place of the aforementioned data and functions, the markup data willbe transmitted, which will have an effect on the display of the visualelement on the client equipment.

Different representations of the visual elements are realized. Forexample, one replaces at the beginning of the film a portion of theoriginal film with a video sequence that presents the name and theaddress of the user. One also uses tools of the “picture in picture” ortechniques of overlay of images, to insert an image containing a messageor an identifier of the client equipment in the video, or other toolsalready existing in the numerical decoders present on the market for theinsertion of text in the video films, techniques well-known to theexpert. The displayed portions of text have changing colors, as well asthe background of the font. They appear for certain ones on only oneimage and for others on a whole series of images. The spacing betweenthe letters constituting the message is variable. The fonts ofcharacters used change. The content of the messages consists of messagesof identification of the client such as name, address or client ortelephone number and information intended for the client, like messageswith legal consequences informing the client of rights and obligationsin relation to the copy of the film, of the type “Mr. Untel, this filmcan be seen only by you and your family and in no case can a copy andcommercial distribution be made.”

In another example, the visual elements contain messages intended forthe client of the type email, short message (SMS or “Short MessageService”), or messages sent by the server that protects the audiovisualrights.

Advantageously, one can display visual elements by modifying the blocksconstituting the structured binary stream in the case of a MPEG-2stream, for example.

Advantageously, in a stream of the type MPEG-4, one can carry outvisible markup while inserting the markup data thanks to one or moreadditional multi-media tracks in the numerical binary stream. Thisadditional video stream can then contain only visual elements whichappear on video streams already present. Standard MPEG-4 also allows,thanks to the management of scenes, to change the position of displayand the animation of this new video track containing the visualelements.

One interest of this solution is that it allows a fast and simpleauthentication of the client for whom a copy of a video program isintended. The aforementioned authentication is always possible for thepossible numerical or analog copies of the aforementioned program.Therefore, a person found in possession of a copy of the aforementionedprogram, whatever the backup is: analog or numerical, must have a copythat the visual element personally identifies. If the visual elementpresent on the aforementioned copy does not identify its current holder,then it is the case that the aforementioned copy is fraudulent: itsholder does not have the rights associated with the holder'sconsumption, and the identified person by the visual elementdistributed, voluntarily or not, a copy of the aforementioned programfor which the holder does not have the rights of distribution.Therefore, identification of the author of a pirate copy of a film islargely facilitated compared to other solutions available. On the onehand, it no longer requires a comparison between the copy to be testedand the original since the visual element is visible and directlycomprehensible. On the other hand, it does not require a complex devicesince simple viewing is enough to identify the person at the origin of acopy.

This invention provides a procedure for the suitable and personalizedvisible marking of video films to dissuade illicit copies and thatapplies to every structured numerical video content, with any systembuilt on the client-server principle described, as with any system ofdistribution of DVDs and CDs disks. An example is the addition ofvisible marking in the “screeners.” The “screeners” are VHS or DVDcopied films ready to be distributed in the movie theaters and which areaddressed to professionals of the cinema (critics, distributors) incertain countries such as in the United States. They need to have aversion of films in advance to be able to make their criticism, toevaluate the interest of a film before its release. The “screeners” arethus essential to the operation of the cinematographic studios. However,they are one of the main sources of pirated films not yet released onDVD (the pirating related to the “screeners” affects films right beforeor right after their release in the movie theaters).

By applying this invention based on an analysis of the video stream andseparate transmission of a modified principal stream and additionalinformation containing the markup data, on the “screeners'” DVD, theirrecipients will no longer be able to make numerical copies anddistribute them. For example, for each of the “screener” recipients, oneintroduces into the film the name and address in a visible way, if theperson distributes the film, the name will appear clearly at all theplaces where the recipient will distribute the film, which will revealthe source of unauthorized duplication. In this manner, one carries outa visible and personalized marking, different from the traditionalwatermarking which is, with the naked eye, invisible. A simple exampleis the overlay of the name of the person or the company for which the“screener” is intended on the video displayed, so that it is displayedpermanently on the screen. Thanks to this personalized marking, if ananalog video is encoded to be distributed on the Internet in an illicitmanner, it will carry the signature of the person from which the piratedcopy originated. Until now it was very simple and not very risky to makea copy of its “screener.” This explains the success of this form ofpirating.

The visual elements introduced into video stream remain present in thestream even if the latter undergoes various modifications and numericaltransformations such as decompression, analog-digital transformation,numerical change of format, distortion, re-compression, assembly,rotation, and geometrical handling of the image, provided that theyleave the video comprehensible. The reason is that these modificationsattempt to avoid deteriorating the contents of the images of the videoso that it remains comprehensible. Therefore, since the visual elementis voluntarily displayed and comprehensible, it will also remain soafter one of these processing procedures.

The technology described in this invention is complementary to otherprotection and traceability technologies, such as watermarking, whichcan be introduced into the digital video stream starting from the markupdata which in this case allows the display of a visible mark and aninvisible mark. This invention indeed makes it possible to add, inaddition to a visible marking, invisible modifications in the streamaccording to methods of “watermarking” (embossing or tattooing), and/orof “fingerprint” (a technique used to distinguish various copies of thesame contents following its recipient by comparing the watermarkinserted in the video with those backed up beforehand in a data base ofassociated data), and/or of stéganographie (a technique allowing todissimulate information within contents of the type text, video, orimage), on distributed video streams.

Others have already thought of using this personalized watermarkingwithin the framework of the protection of digital films by encoding aversion of the film for each user, unless these solutions are notcommercially viable. This invention circumvents the problem ofcompressing the film for each client since all who receive the samecompressed film, only the markup data sent differs from one client toanother and is personalized for each client. Thanks to this invention,studios can freely use the “screeners” to promote their films andcounter the main source of illicit copies of high quality films.

An example is the introduction of the name and address of the person forwhom the film is intended and which should not distribute it byreplacing parts of image of origin by a new image in conformity with theformat of the video and containing the coordinates of the client. Forexample, the case of MPEG-2 streams is interesting because the films inDVD or DVB format are the result of it. A numerical MPEG-2 video streamconsists of sequences of images (plans or frames), gathered in groups ofimages “Groups Of Pictures” (GOPs). An image can be of type I (Intra), P(Predicted), or B (Bidirectional). Images I are the images of reference,they are entirely encoded and are, thus, of large size and do notcontain information concerning the movement. The frames P are planspredicted starting from the preceding plans I and/or P, thanks tovectors of movement in only one direction, called from now on “forward.”The plans B are known as bidirectional, they are related to the plans Iand/or P preceded or followed by movement vectors in the two temporaldirections (“forward” and “backward”). The movement vectors representtwo-dimensional vectors used for the compensation of the movement. Theyprovide the difference in coordinates between a part of the currentimage and a part of the reference image.

An image can be organized by “slices” or sections, for example, as inMPEG-2. An image or a frame consists of macro blocks that themselvesconsist of blocks. A manner of introducing complementary modificationinformation is to encode the name and address of the user in a number ofblocks, macro blocks, or “slices” with the same format as the originalstream, in fact, MPEG-2, to replace the original macro blocks with themacro blocks built for the modification in each image.

Another possibility is to superimpose the complementary informationintroduced in the existing macro blocks. This substitution or thissuperposition is carried out thanks to the complementary informationsent by the server to the client and which contains data and functionsto be carried out on the modified principal stream to obtain theoriginal marked stream. Thus, for the parts of the image that do nothave to bear an identification mark in the form of a visual element, thecomplementary information specifies to the client equipment whichfunction to apply to principal stream to obtain the original stream. Forthe parts of the image that do have to support the affixing of a visualelement, complementary information specifies to the client equipmentthat it replace the corresponding structures (“slices,” macro blocks andblocks) of the modified principal stream by the structures conveyed bythe markup data, contained in complementary information, whichcorresponds to an image containing the message (text or other) todisplay on the client equipment to identify the associated client.

The invention will be better understood upon reading an example of theinvention, while referring to FIG. 1.

In the example, the invention concerns a video sequence encodedaccording to the MPEG-2 format, without that it constitutes a reductionof the range of the invention.

The encrypted digital video contents are contained on DVD (1) andencoding used is based on a technique, based on well known keys. Thecontents of the DVD (1) are sent to a numerical decoder of the client(4) also called “Set Top Box” (4) via a video acquisition interface (3).The video contents of the DVD (1) are then transferred within the SetSignal Box (4) to a decoding module (41). The module of decoding (41)deciphers the contents of the DVD (1) and sends the decoded video inMPEG-2 format (44) to the decoding module of decoding MPEG-2 (42) of theSet Top Box (4). The MPEG-2 decoding module decodes the deciphered video(44) and transmits the video that is ready for display (45) to themarking module differently called “composition module” (43) of theSet-Top-Box (4). Composition module (43) is used to affix a visualelement of personal identification to the video stream (45) transmittedby decoder MPEG-2 (42) according to the markup data (12) read through aninterface of acquisition of the markup data (5). The markup data (12)are read from a chip card (6). The video contents, ready and marked in apersonalized and visible way (11), are then displayed on the displaydevice, of type television or monitor (8), of the client. If the clientwants to record the marked video stream (11) on a storage device (9) ofthe type hard disk, DVD, CD, or VHS cassette, the recorded content willcontain the visual element of personal identification affixed by thecomposition module (43) and is thus not commercializable.

In another example, the encrypted digital video contents are receivedfrom a satellite or parabolic (2) reception device and forwarded towardsthe Set-Signal-Box (4) via a video acquisition device (3).

In another example, the markup data (12 bis) are received by theacquisition interface of the markup data (5) from a remote server (7).

In a variation of the example, the remote server (7) is a server thatprotects the audiovisual rights and is connected to a server ofelectronic mail (13) like an email server or a text server (SMS or“Short Message Service”) or a server used for the follow-up of thecustomers renting of the protected video. This electronic mail server(13) occasionally sends to the server (7) protecting the audiovisualrights at least a message intended for the client to which the decoder(4) belongs. This message is then included in the markup data (12 bis)so that the aforementioned message can be displayed on the screen (8) ofthe client.

The operation of the composition module (43) will be better understoodupon the reading of the following realization example, exhibited in thedrawings of FIG. 2.

The markup data (12) coming from the chip card (6) are read by aninterface of the type chip card reader (5) and sent to an interpretationmodule of the markup data (431). This interpretation module (431) is apart of the composition module (43). The purpose of the module ofinterpretation (431) is to transform the binary data of the markup data(12) into markup information (435). Therefore, in the example ofinterest, the interpretation module (431) transforms the markup data(12) into a string of characters that contain an identifier of theclient (435), as, for example, name. This character string is sent tothe module that determines the form of the visual element (432) whichdecides to introduce the aforementioned string (435) at a randomlocation in the marked video (11) to generate markup objects (436)likely to be displayed on a screen. The module that determines the form(432) also determines the color, character font, size, and duration ofappearance of the character string (435) on the screen. Once all of thecharacteristics of the display of the visual element (436) contain thecharacter string (435) defined in a manner to generate markup objects(436), the visual elements (436) are transferred to a module thatoverlays the objects in the video (433). The module that overlays theobjects (433) adds the visual element (436) to the video (45) to obtaina video marked in a personalized way (11) in which the character string(435) is embedded.

In another example, interpretation module of the markup data (431)extracts the markup data (12) from an image (435). The image (435)contains an identifier of the client such as name and address written ina colored framework. The image (435) is transmitted to the module thatdetermines the form (432) and which decides in a random way the positionof the image (435) on the video marked (11) to generate a markup object(436). The module that embeds the object in the video (433) thenprocesses the video (45) to affix to it the element of personalization(436) to make a marked video (11).

In another example, the interpretation module of the markup data (431)generates, in addition and within the markup information (436), adigital signature (435) starting from the markup data (12). Digitalsignature (435) is an identifier of the client and/or viewing sessionand/or client device and/or a message. The signature is transmitted tothe module that determines the form (432) that will generate a motif forwatermarking (436), invisible to the human visual system andcharacteristic of the aforementioned signature (435) so that the inverseoperation of the recovery of the signature from the watermarking motifis possible, possibly by using the contents of the data base of clientprofiles (702). The motif for invisible watermarking (436) is overlaidin the video (45) by the overlay module (433) after its decoding by theMPEG decoding module (42), via a series of invisible modificationswithin the video (45) after decoding. Generation of a watermark (436)invisible to the human visual system starting from the digital signature(435) is carried out according to techniques of “watermarking,” of“fingerprint” (watermarking identifying the recipient of a video stream)or of traditional stéganographie.

A non restrictive example is as follows: the numerical signature isencrypted according to a traditional encrypting technique, and thenumerical string thus obtained is repeated to generate a frame ofsamples of pseudo random noise of which the number of samples is equalto the number of pixels of each image of the video be to watermarked(45). Each bit of this pseudo random noise is then assigned to a pixelwhich can have the value 0 or 1. The pixels thus obtained are arrangedin a manner to form columns and rows. This technique leads to obtaininga binary image (436) consisting of pixels of value 0 or 1. The “0” andthe “1” that constitute this image are then added to the LSB (leastsignificant bit) of each pixel of each image of the video (45) by theoverlay module (433), thus introducing modifications invisible to ahuman eye and characteristic of the digital signature (435) into thevideo (45). It is then possible to detect and recover the digitalsignature at a later stage by carrying out a comparison between theoriginal video stream and the reconstituted and marked video stream(11). In the case that the original LSB and the recomposed LSB aredifferent, the detected bit is “1,” in the opposite case, its value is“0.”

Another example comprises modifying pixels only at certain points invideo stream (45), the aforementioned points being determined with theaid of the exploitation of a numerical key stored in the client profilesdatabase server (702). The aforementioned modification comprisesreversing the LSB when the bit to be coded is “1,” and leaving itunchanged if its value is “0.” Still, a pseudo random noise is obtainedby encoding the signature in a way to be inserted in the video (45). Adedicated numerical key is then used to calculate the positions of themodified pixels and stored on the client profiles database server (702)to be able to detect and recompose the message encoded at a later phaseof detection and recovery of the numerical key. During this last phase,the detection module determines positions of the modified pixels withthe aid of the dedicated numerical key obtained from the client profilesdatabase server (702) and then compares the value of the pixels of theoriginal video stream with those of the video stream to test at each ofthese points.

More generally, techniques used within the framework of “watermarking”technologies, “fingerprinting” and stéganographie, are used for:

determining the points or zones of the image of the video (45) to modifyfor inserting the signature;

formatting the binary frame to insert in the video, generated from thenumerical signature (435), including, in particular, but notexclusively, possible error codes of redundancy and encrypting; and

modifying video stream (45) to integrate the watermarking motif (436).

This invention can combine affixing a visual element to the video streamwith a secured stream distribution system. One example is describedbelow in reference to FIG. 3. In that example, the video is scrambled bya system that concerns a nominal stream format comprising a successionof frames comprising at least one numerical block gathering a selectednumber of coefficients corresponding to simple video elements encodednumerically according to a mode specified inside the concerned streamand used by all the video decoders that are able to decode it to be ableto display it correctly. This procedure comprises: a preparatory stagethat comprises modifying at least one of the aforementioned elements(for example, the coefficients) of the original stream; a transmissionstage:

of a principal stream conforming to a nominal format (201), comprisingthe plans containing the elements that are modified during thepreparatory stage from a video server (200) and

through a channel separate from that of the aforementioned principalstream (201) of complementary numerical information (202) that allowsreconstruction of the original stream from a calculation on thedestination equipment (400) as a function of the aforementionedprincipal stream (201) and the complementary information (202).“Complementary information” (202) is defined as a collection comprisingdata (for example, of the coefficients describing the original numericalstream or extracts of the original stream) and functions (for example,the substitution or permutation function). One function is defined tocontain at least an instruction that matches up the data and theoperators. The complementary information (202) describes the operationsto execute to recover the original stream from the aforementionedmodified stream.

In this example, the complementary numerical information (202) containsin addition to the data and functions necessary for the reconstitutionof the nominal stream, the data and functions carried out with the aidof numerical routines (collections of instructions) devoted to add avisual element to the reconstituted video (11).

In this example, the “Set-Top-Box” (400) is located at the client.Reconstruction of the original marked stream (11) takes place on thedestination equipment (the STB) (400) from the modified principal stream(201) and the complementary information sent in real time (202). Theclient equipment (400) includes a binary stream composition device (401)and a decoder (402). The binary stream composition device (401) modifiesthe modified principal stream (201) in a manner to conform to thefunctions and data included in the complementary information (202) to:on the one hand, return the modified principal stream (201)comprehensible to a human eye; on the other, add to the reconstitutedstream a visual element, the visual element being an identifier of theclient or a message that is intended for the client. The binary streamthus generated (403) is transferred to the decoder (402) which decodesit to generate a marked video (11). The marked video (11) is displayedon the display device of the client (8). If the client or a third partywants to record the marked video stream (11) on a storage device (9) oftype hard disk, DVD, CD, or VHS cassette, the recorded contents containthe visual element of personal identification.

The additional information (202) is sent to the equipment by a serverthat manages the rights of the client (700). This server (700) hasaccess to the original complementary information (701) allowingreconstitution of the unmarked modified principal stream (201) and froma data base of client profiles (702). The server sends permanently theoriginal complementary information (701) and the markup data specific tothe client calculated thanks to the client data base (702).

When the client wishes to view the video contents, it addresses arequest to the server that manages the rights of the customers (700).This server checks by a standard means (for example, a data base) therights of the client for the requested video contents and if the clientis authorized to view the video contents, the server that manages therights of the customers (700) sends the complementary numericalinformation (202) as the reading of the contents on the client equipmentproceeds.

In another example, the server (700) decides in real time to sendcomplementary information (202) personalized as a function of the client(400) to whom it is addressed by sending either a part of originalcomplementary information (701) or the markup data specific to theclient calculated thanks to the data base of client data (702). Thus,the client does not receive the complementary information (202) thatwould enable the client to display the nominal stream where anidentification mark is present.

In another example, the server (700) decides in real time to sendcomplementary information (202) personalized as a function of the client(400) to which it is addressed by sending either a part of the originalcomplementary information (701) or the markup data specific to theclient calculated thanks to the data base customers (702), or a part ofthe original complementary information (701) modified according to thedata base of client data (702). The modifications made to thecomplementary original information comprise in particular, but notexclusively, adding instructions intended for the module of composition(401) in a manner to force it to reverse the LSB of certain visualcoefficients of the stream such as the coefficients. DC, for example.The absence or presence of an inversion of a LSB will allow, at the timeof a later stage of recovery of the digital signature of the streamcomprising comparing the original video stream with the marked videostream (11) to recompose a bit of the digital signature. More generally,modifications made to the complementary information are used to insertan invisible modification within the reconstituted and marked videostream (11). They thus comprise indicating to the composition module(401) how to insert a digital signature into the digital stream (403)according to any method of “watermarking,” “fingerprint,” or existingand applicable stéganographie, on a video stream that is stillcompressed (before decoding: in particular on coefficients in thefrequency domain).

In another example, the server (700) which sends complementaryinformation (202) to the decoder of the client (400) connects to anelectronic mail server (13) which can be an email server, a text server(or SMS), or an instantaneous electronic mail server (such as forexample “IRC”/“Internet Relay Chat”). This electronic mail server (13)relays messages intended for the client that possesses the clientequipment (400) for which the complementary information (202) isintended, towards the server that protects the audiovisual rights (700).The audiovisual protection server (700) then inserts these messageswithin the complementary information (220) so that the aforementionedmessages are displayed on the display device (8) of the client for whichthey are intended.

1. A process for distributing a video stream to a multitude ofdestinations comprising marking by adding to the video stream at least avisual element such that the marking is applied to an original videostream common to selected recipients, and personalized for a leastportion of the recipients by addition of a visual element specific todestination equipment.
 2. The process according to claim 1, wherein thevisual element is generated in two stages comprising processing themarkup data in any format to generate markup objects that describe thevisual element to display, and adding the visual element to the videostream.
 3. The process according to claim 2, wherein adding the visualelement is accompanied by adding invisible modifications.
 4. The processaccording to claim 3, wherein at least one addition is carried outbefore decoding the video stream in the destination equipment.
 5. Theprocess according to claim 3, wherein at least one addition is carriedout after decoding the video stream in the destination equipment.
 6. Theprocess according to claim 3, wherein the invisible modifications arecharacteristic of a digital signature, the digital signature beingdetectable by an algorithm appropriate for detection applied to thevideo stream containing the invisible modifications.
 7. The processaccording to claim 6, wherein the digital signature is obtained frommarkup data.
 8. The process according to claim 2, wherein the markupdata are different and personalized for every client.
 9. The processaccording to claim 8, wherein the visual element introduced in the videostream is different and personalized for every client.
 10. The processaccording to claim 9, wherein the visual element is an identifier of theclient during display of the marked video stream.
 11. The processaccording to claim 9, wherein the visual element includes a messagedestined for the client.
 12. The process according to claim 1, whereingenerating markup objects from the markup data makes it possible to varyposition on a display screen, color, spacing, geometry, and presence ofthe visual element, during display of all or a portion of the videostream.
 13. A process according to claim 12, wherein adding the visualelement to the video stream is carried out on a multi-media serverequipment from which the video stream is dispatched to the client in alater phase.
 14. A process according to claim 12, wherein adding thevisual element to the video stream is carried out on the clientequipment.
 15. A process according to claim 14, wherein the markup datacome from a server that protects audiovisual rights when viewing thevideo stream.
 16. A process according to claim 14, wherein the markupdata come from a module present on the client equipment.
 17. A processaccording to claim 15, wherein viewing the video stream is conditionalupon connection to the server that protects the audiovisual rights. 18.A process according to claim 15, wherein the server connects to a database of client profiles including the markup data associated with everyclient.
 19. Apparatus for distributing a video stream marked accordingto the process of claim 1, comprising: a standard decoding module of aformat of the video stream, and a composition module that interprets themarkup data and includes the visual element in the video stream.
 20. Theapparatus according to claim 19, further comprising a chip card readerlinked to a chip card that contains the markup data.
 21. A system forfabricating a marked stream according to the process of claim 1,comprising equipment for distributing a video stream comprising astandard decoding module of a format of the video stream, and acomposition module that interprets the markup data and includes thevisual element in the video stream, means for storing the video stream,means for storing the markup data, a display device of the video streamand a storage device of the modified video stream.
 22. A system forfabricating a marked stream according to the process of claim 1,comprising equipment for distributing a video stream comprising astandard decoding module of a format of the video stream, and acomposition module that interprets the markup data and includes thevisual element in the video stream, a storage device, a markup datastorage device, a display device of the video stream and a storagedevice of the modified video stream.